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Asteroids have historically been observed from Earth. The first close-up observation of an asteroid was made by the Galileo spacecraft. Several dedicated missions to asteroids were subsequently launched by NASA and JAXA, with plans for other missions in progress. NASA's NEAR Shoemaker studied Eros, and Dawn observed Vesta and Ceres.
These are composed primarily of S-type asteroids, whereas the neighboring Hungaria family includes some E-types. [101] The Phocaea family orbit between 2.25 and 2.5 AU from the Sun. [102] Skirting the outer edge of the asteroid belt is the Cybele group, orbiting between 3.3 and 3.5 AU. These have a 7:4 orbital resonance with Jupiter.
S-type asteroids, with an astronomical albedo of typically 0.20, [1] are moderately bright and consist mainly of iron- and magnesium-silicates.They are dominant in the inner part of the asteroid belt within 2.2 AU, common in the central belt within about 3 AU, but become rare farther out.
The asteroid and comet belts orbit the Sun from the inner rocky planets into outer parts of the Solar System, interstellar space. [16] [17] [18] An astronomical unit, or AU, is the distance from Earth to the Sun, which is approximately 150 billion meters (93 million miles). [19]
Asteroid families become visible as distinct concentrations when asteroids are plotted in the proper orbital element space (i p vs a p).Some prominent families are the Vesta, Eunomia, Koronis, Eos, and Themis family located in different (colorized) regions of the asteroid belt.
Astronomers believe that the impact of asteroids crashing into our planet may have helped deliver water and other elements to early Earth, so finding evidence of water on asteroids could support ...
While many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia, and water. The Kuiper belt is home to most of the objects that astronomers generally accept as dwarf planets: Orcus, Pluto, [5] Haumea, [6] Quaoar, and Makemake. [7]
The surfaces of both asteroids are weak, much weaker than loose sand," Barnouin added. The researchers concluded that Dimorphos is composed of material that flew off the equatorial region of ...